The invention generally relates to vehicle control, and more particularly relates to a method for determining vehicle status quantities which are needed in particular to realize or enhance automotive-vehicle control systems.
From European Patent EP 444 109 B1, a method for controlling the movement of an automotive vehicle is known that is based on the detection of tire prints. Beside tire sensors which detect the tire contact patch, still other sensors are used to detect wheel speeds, angle of turn, position of the wheel suspension, acceleration of the center of gravity, etc. This known control method provides that, by means of the tire print sensors, forces and moments are measured which act on the individual tires. These measuring results are, along with the information delivered by the other sensors, used to control the movement of the automotive vehicle. The method is provided in particular for vehicles on which all wheels can be propelled and steered.
DE 39 37 966 C2 sets forth a method for determining of the friction force conditions between vehicle wheel and road, in which method the deformations occurring in the vehicle tire in horizontal and in normal direction while passing the tire contact patch are detected and are evaluated for determining the forces acting on the tires. The friction coefficient is then determined from the ration between the horizontal force and the normal force.
The present invention determines, on the basis of various tire sensors, vehicle status quantities that are utilizable in particular for automotive-vehicle control systems with the precision and reliability required by such systems.
The present invention fulfills the objects of the present invention in that, on the basis of measured quantities that are obtained by means of tire force sensors and that reflect tire longitudinal and lateral forces as well as tire vertical forces, the methods of the present invention obtain the yaw rate and/or acceleration, the steering angle and the side slip angle of the automotive vehicle as well as the vehicle velocity and vehicle acceleration are obtained under consideration of correction quantities.
The method according to the present invention for the determination of vehicle status quantities and a control founded thereon, is thus based on the moments and forces occurring directly at the tire. By this means already, all influencing quantities are detected, and misinterpretations that go back to ambiguous sensor signals or processing errors are avoided or impeded. By consideration of corrective quantities, the safety and reliability of the determination of vehicle status quantities and the consideration of the respective driving situation are still significantly increased or improved, respectively.
According to an advantageous embodiment of the invention, the tire-force dependent quantities obtained by means of tire sensors, the intermediate quantities, and the components of these quantities are weighted in the corrective steps in dependence on further measured quantities that, e.g., are established by means of conventional sensors, such as wheel velocity sensors etc., and/or on quantities which reflect the momentary driving situation (such as cornering, driving straight, friction coefficient, etc.). According to the invention, additional quantities depending on engine torques, engine speed, transmission gear, etc., can be detected and evaluated for weighting the vehicle status quantities. Thereby, for instance, a very extensive, very precise adaptation of the control to very different situations can be achieved. Furthermore, the error safety and the timely recognition of possible defects is enhanced.
According to a further embodiment of the invention, the vehicle status quantities or components of these quantities are weighted in separate corrective steps as the quantities determined by the tire sensors are combined with respective quantities determined by conventional sensor devices and/or by the current driving situation and by further processing these combined quantities as corrected measured quantities. Here, it has been found useful to obtain and evaluate the angular yaw velocity, the longitudinal component of the vehicle velocity and the lateral component of the vehicle velocity in separate corrective steps.